Ordinarily I'm also the type who likes to be able to install just what they need. But in most cases installing just what you need results in a smaller/faster program. Considering that Opera is already smaller/faster than basic Firefox on my system, I'll live with just ignoring what I don't use.

Plus I've found that after finding the time to give some features I initially ignored a try, I find them quite useful after all (like mouse gestures).
If I'd tried Firefox first, I'd probably have liked it. It's a good browser. But I'm so used now to using a ton of Opera's features (especially for webmastering) that I'd have to keep track of a ton of extensions to do the equivalent in Firefox. I'm too lazy.

As for ads, I use the free version with Google text ads at work, and it's in a little thin strip at the top of the screen. Not a big deal for such a nice browser. (Plus it's kind of funny seeing what shows up for each site I visit...)
I registered the one I use at home, since $39 for a program I literally use for at least 5 hours a day nearly every day is a fair deal, IMHO. Heck, don't we sometimes pay $50+ for games we play for about 20 hours a couple times?
Anyway, when it comes to which types of features a person likes in a browser, it's up to personal preference, I'm not going to dispute that. I just think that the money/ad thing in specific is a silly thing to get caught up on.
Peace & Luv, Liz